1. Field of the invention
The present invention relates to a laser projection type display unit, and in particular to a laser projection type display unit to arbitrarily display characters and the like on screen by single stroke writing with laser beam.
2. Description of Background Information
Conventionally, the apparatus of this type has such a structure that laser beam emitted from a laser light source is deflected two-dimensionally by a galvanometer scanner, which is a two-dimensional deflection means, and is projected on screen. By controlling galvanometer scanner according to the display data by giving appropriate display data to the scanner drive, the characters and the like are arbitrarily displayed on the screen by single stroke writing.
When "12" is displayed, for example, as shown in FIG. 1 in an apparatus of conventional type, the difference in lightness is dmadebetween a.fwdarw.b, c.fwdarw.d and b.fwdarw.c by increasing the scanning time of b.fwdarw.c compared with the scanning time of a.fwdarw.b and c.fwdarw.d because laser beam is continuously projected on the screen. However, the so-called tailing phenomenon occurs between light spots because laser beam is continuously projected. Thus, it has been difficult to display a group of independent points in the case of the conventional arrangement.